1. Field of Invention
The invention relates to a light-emitting module, a diffusion unit and a diffusion sheet.
2. Related Art
Since the liquid crystal display (LCD) technology has been developed recently, the LCD device gradually replaces the conventional CRT (cathode-ray-tube) display device. The liquid crystal in the LCD device can not emit light by itself, so a backlight module is necessary for the backlight light source of the LCD device.
As shown in FIG. 1, a conventional backlight module 1 includes a light source 11, a back plate 12, a diffusion plate 13 and a diffusion film 14. For example, the light source 11 includes a plurality of CCFLs (cold cathode fluorescent lamps), which are separately disposed in the back plate 12. The diffusion plate 13 is disposed on the light source 11, and the diffusion film 14 is stacked on the diffusion plate 13.
As mentioned above, the diffusion plate 13 can homogenize the light emitted from the light source 11 so as to reduce the non-uniformity of the light, which is similar to the function of the diffusion film 14. In addition, since the thickness of the diffusion plate 13 is larger (about 1.5 to 2.0 mm), the diffusion plate 13 can achieve the function of supporting the diffusion film 14.
However, the thickness as well as the material cost of the diffusion plate 13 is greater than those of the diffusion film 14. In addition, the light emitted from the light source 11 may generate more energy loss after passing through the thicker diffusion plate 13, so that the brightness of the backlight module 1 is decreased.
Therefore, it is an important subject to provide a backlight module, a diffusion unit and a diffusion sheet that can reduce the material cost of the diffusion sheet and increase the brightness of the outputted light.